Switch actuated by the separation of two coupled units

ABSTRACT

A switch alters an electrical circuit when two normally coupled units are separated. The switch includes a housing attached to one of the coupled units, and this housing has a plunger mounted therein which moves inwardly and outwardly with respect to the housing. At its inner end the plunger has a contact which moves toward and away from the fixed contact as the plunger moves so that the circuit is complete when the two contacts are engaged and disrupted when the contacts are separated. A spring urges the plunger to its innermost position in the housing, while a spacer grips the outwardly exposed portion of the plunger and normally prevents the plunger from moving inwardly under the influence of the spring. A cable attaches the spacer to the other of the two coupled units so that when the coupled units separate the spacer is disengaged from the plunger, thereby freeing the plunger and enabling the spring to move it into the housing to alter the circuit.

United States Patent Westenhaver [451 Sept. 5, 1972 [72] Inventor: KeithG. Westenhaver, 305 Bourn Ave., Columbia, Mo. 65201 [22] Filed: May 13,1971 [21] Appl. No.2 143,109

[52] US. Cl. ..200/61.19, 340/52 D [51] Int. Cl. ..H01h 27/04 [58] Fieldof Search ..200/61.19,153 M [56] References Cited UNITED STATES PATENTS2,928,912 3/l960 Molnar ..200/61.19 3,210,494 10/1965 Murdock..200/61.l9 2,802,074 8/1957 Pass ..200/61.l9 2,844,675 7/1958 Edgar..200/61.19 3,062,326 11/1962 Jones et al. ..200/61.19 X

Primary Examiner-Robert K. Schaefer Assistant Examiner-M. GinsburgAttorney-Gravely, Lieder & Woodruff [57] ABSTRACT A switch alters anelectrical circuit when two normally coupled units are separated, Theswitch includes a housing attached to one of the coupled units, and thishousing. has a plunger mounted therein which moves inwardly andoutwardly with respect to the housing. At its inner end the plunger hasa contact which moves toward and away from the fixed contact as theplunger moves so that the circuit is complete when the two contacts areengaged and disrupted when the contacts are separated. A spring urgesthe plunger to its innermost position in the housing, while a spacergrips the outwardly exposed portion of the plunger and normally preventsthe plunger from moving inwardly under the influence of the spring. Acable attaches the spacer to the other of the two coupled units so thatwhen the coupled units separate the spacer is disengaged from theplunger, thereby freeing the plunger and enabling the spring to move itinto the housing to alter the circuit.

11 Claims, 5 Drawing Figures SWITCH ACTUATED BY THE SEPARATION OF TWOCOUPLED UNITS BACKGROUND OF THE INVENTION This invention relates ingeneral to switches and, more particularly, to a switch which isactuated by the separation of two normally coupled units.

Many vehicles and other devices are normally coupled with other vehiclesor devices so that in use they operate as coupled units. Nevertheless,the units are still separable for purposes of storage, repair, and thelike. In many of these combinations considerable damage or injury mayresult should the coupled units become detached while operatingtogether. For example, should a trailer break loose from its towvehicle,

the trailer brakes should be applied immediately, lest the trailer runfreely and damage property or perhaps injure a bystander. Similarly,should a boat, tractor, or any motor driven vehicle lose its driver, themotor should be shut down immediately. For this application, the spacercable would be fastened to the driver.

SUMMARY OF THE INVENTION One of the principal objects of the presentinvention is to provide a switch which operates upon the separation ofnormally coupled units. Another object is to provide a switch of thetype stated which is simple and durable in construction, easy tomanufacture, and highly reliable. A further object is to provide aswitch of the type stated as easily installed on normally coupled unitsof many different varieties and uses. An additional object is to providea switch for activating the brakes of a trailer should the trailer breakaway from the vehicle towing it. These and other objects and advantageswill become apparent hereinafter.

The present invention is embodied in a switch having a base means on oneof two coupled units. A plunger is mounted on the base means and carriesa contact which engages another contact mounted on the base means.Retaining means holds the plunger in one position and is connected tothe other coupled unit so that when the units separate the retainingmeans is disengaged from the plunger and the plunger is free to changeposition and thereby alter the circuit in which the contacts arelocated. The invention also consists in the parts and in thearrangements and combinations of parts hereinafter described andclaimed.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings which form partof the specification and wherein like numerals and letters refer to likeparts wherever they occur:

FIG. 1 is a perspective view of a trailer and tow vehicle combinationprovided with a switch constructed in accordance with and embodying thepresent invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a fragmentary sectional view showing the spacer block detachedfrom the shaft of a plunger and the contacts in engagement; and

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2 and showingthe spacer in elevation.

DETAILED DESCRIPTION Referring now to the drawings, 1 designates aswitch including (FIG. 1) a switch housing 4 which constitutes a basestructure and has a pair of sidewalls 6 and 8, a pair of end walls 10connected across the ends of the side walls 6 and 8, and a base wall 12to which the sidewalls 6 and 8 (FIG. 2) and end walls 10 are afiixed.The base wall 12 projects beyond the end walls 10, forming mounting tabs14 for securing the housing 4 to a supporting structure. The housing 4also includes a top wall 16 which is connected to the edges of thesidewalls 6 and 8 and end walls 10, forming a closure for the interiorof the switch housing 4.

The sidewall 8 of the housing 4 is provided with an aperture 18 (FIG. 2)which aligns with a guide sleeve 20 (FIGS. 2 and 3) disposed within theinterior of the housing 4. This sleeve 20 is provided at one of its endswith a flange 22 which abuts against the interior surface of thesidewall 8 and is secured thereto. Thus, the guide sleeve 20 is carriedby sidewall 8 and projects inwardly therefrom with its axesperpendicular to the wall 8. The guide sleeve20 receives an elongatedshaft 24 which is somewhat longer than the sleeve 20 and projects beyondboth ends thereof; The fit between the shaft 24 and the sleeve 20 issuch that the former slides freely within the latter, and no binding orappreciable friction exists. At its inner end the shaft 24 is fittedwith a dielectric end block 26 having an electrical contact 28 fastenedagainst its end face which is presented away from sleeve 20. Not onlydoes the dielectric block 26 carry the end contact 28, but it alsoserves as a stop for preventing complete withdrawal of the shaft 24 fromthe sleeve 20 and aperture 18. The dielectric block 26 is rectangular inshape and has one of its edges presented close to the top wall 16 sothat the block 26 and shaft 24 do not rotate in the housing 4 (FIG. 3).

The shaft 24 is urged inwardly by a coil spring 30 which encircles boththe sleeve 20 and the shaft 24. The ends of the spring 30 bear againstthe dielectric end block 26 and the sleeve flange 22. At its outer end,the shaft 24 is provided with a knob 32 which projects radiallyoutwardly from the shaft 24. Thus, the knob 32 is presented externallyof the housing 4 for manual manipulation. The elongated shaft 24, thedielectric end block 26, and the knob 32 in combination constitute ashiftable plunger.

Fastened firmly against the sidewall 6 and located directly opposite tothe dielectric end block 26 on the shaft 24 is another dielectric block34 (FIGS. 2 and 3) and this block, like the block 26, carries anelectrical contact 36 which is fastened against the inwardly presentedend face thereof. Indeed, the contact 36 aligns with the contact 28 onthe end block 26 at the end of the shaft 24 so that when the shaft 24 isnot obstructed (FIG. 4), the spring 30 will urge the blocks 26 and 34together and bring the contacts 28 and 36 into engagement.

The switch housing 4 also contains a bulb socket 40 (FIG. 2) which isfastened against the sidewall 6 and opens outwardly through an aperture42 in that wall. The socket 40 retains a bulb 44 having a center contactwhich bears against a base contact 46 at the inner end of the socket 40.The base contact 46 is electrically isolated from the remainingstructure of the socket 40,

which is grounded to the housing 4, and is connected to the electricalcontact 36 and the fixed dielectric block 34 by a wire 48. The bulb 44is covered by a lens 50 which is also fastened to the side wall 6, butmay be removed therefrom to provide access to the bulb 44.

The contact 28 on the movable dielectric block 26 is attached to a wire56 which leads away from the housing 4 and is connected to one terminalof a source 54 of electrical energy such as a battery. The otherterminal of the electrical energy source is connected to ground, or inother words, is common to the housing 4 and the supporting structure onwhich the housing 4 is mounted. The contact 36 on the dielectric block34, in addition to being connected to the wire 48, is connected toanother wire 52 which also leads from the housing 4 and is connected toan electrically operated appliance or device.

As previously noted, the shaft 24 when unrestrained (FIG. 4) will moveinwardly under the force exerted by the compressed spring 30 and willbring the contacts 28 and 36 into engagement, thus completing a circuitthrough the wires 52 and 56.

The contacts 28 and 36 are normally separated, and this separation iseffected by means of a spacer 60 (FIG. 5) which fits between knob 32 andthe sidewall 8 and engages the shaft 24. In particular, the spacer 60includes a relatively narrow tongue 62 which is bifurcated at one end toform a pair of retaining arms 64 having opposed arcuate notches 66.These notches 66 conform to the configuration of the shaft 24 and arespaced apart sufficiently to enable the shaft 24 to fit snugly in them.The opposed inner edges of the arms 64 are further provided with cammingedges 68 which lead up to the notches 66, converging as they do.Fastened against the relatively flat side faces of the arms 64 arespreader blocks 70.

To install the spacer 60 on the shaft 24, the knob 32 is withdrawn fromthe housing 4 to expose the shaft 24, the amount of withdrawal beingsuch that the spacing between the knob 32 and the sidewall 8 exceeds thethickness of the spacer 60 at the spreader blocks 70 thereon. Once theshaft 24 is so withdrawn, the spacer 60 is fitted between the knob 32and the sidewall 8 and its opposed camming edges 68 are brought againstthe cylindrical surface of the shaft 24 on each side thereof. Thereuponthe spacer 60 is forced radially toward the shaft 24, and this causesthe camming edges 68 to pass over the surface of the shaft 24, which inturn spreads the retaining arms 64, causing them to deform in oppositionto the natural resiliency of the material from which they are formed.After passing along the camming edges 68, the shaft 24 encounters thearcuate notches 66, at which time the arms 64 snap together and tightlyengage the shaft surface at the edges of those notches 66.

The disposition of the spacer 60 between the knob 32 and the sidewall 8maintains the shaft 24 in an outwardly presented position and keeps thespring 30 compressed. Thus, the opposed faces of the housing 8 and theknob 32 serve as abutment surfaces which normally abut the side faces ofthe spacer 60. Since the retaining arms 64 tightly engage the shaft 24at the notches 66, the spacer 60 is retained in engagement with theshaft 24 and does not work loose even when subjected to vibrations,jolts and the like.

Nonnally, the housing 4 is mounted on one of two coupled units and thetongue 62 is connected to the other unit by -a cable 72 (FIG. 1) whichextends through the end of the tongue 62 located remote from theretaining arms 64. The cable 72 must be strong enough to withstand atensile force sufficient in magnitude to disengage the spacer 60 fromthe shaft 24 and withdraw it from the housing 4. As an example, thehousing 4 may be bolted to the tongue of an automotive-type trailer T,whereas the steel cable 72 may be attached securely to the tow vehicle Vwhich may be an automobile. Assuming that the trailer has electricbrakes, the wire 52 should lead to the brake circuit and should beconnected such that the electric brakes are energized when the contacts28 and 36 of the switch 1 engage. In such an arrangement detachment ofthe trailer T from the tow vehicle V will pull the spacer 60 from theshaft 24 and will further withdraw it from the space between the knob 32and the housing sidewall 8. Once the spacer 60 is free of the knob 32,the spring 30 drives the end block 26 and shaft 24 inwardly until thecontact 28 on the block 26 engages the contact 36 on the fixeddielectric block 34. When this occurs, the circuit from the battery 54to the trailer brakes is closed so that the forward motion of thetrailer is retarded. In other words, once the contacts 28 and 36 engageeach other current flows from the electrical energy source 54 throughthe wire 56, the engaged contacts 28 and 36, and the wire 52 to thebrake actuating mechanism. The engagement of the contacts 28 and 36 willalso place the battery 54 across the light bulb 44, so that the bulb 44is energized and signifies that the circuit though the switch 1 isclosed.

The switch 1 may also be used as a safety switch for a boat, tractor, orany motor-driven vehicle which requires a driver for control of thevehicle. In such instances the warning light 44 and bulb socket 40 wouldnot be used, and the switch 1 would be wired in series with thedistributor or spark plug, as the case may be, of the vehicle, usingignition type insulated wire. The wire 56 would be connected to thevehicle ignition as above stated, and wire 52 would be connected to thevehicle ground. The cable 72 would be attached to the driver so that ifthe driver were thrown from the vehicle he would withdraw the spacer 60.Consequently, when the spacer 60 is disengaged from the shaft 24, thespring 30 will drive the dielectric block 26 inwardly until the contacts28 and 36 engage, thereby grounding the vehicle ignition system andstopping the driverless vehicle.

Where the actuated device draws considerable current, the switch 1 maybe used to operate a relay switch which in turn opens and closes thecircuit to the actuated device.

The switch 1, of course, may be supplied without the warning lightformed by the bulb socket 40 and the bulb 44 which fits therein.

This invention is intended to cover all changes and modifications of theexample of the invention herein chosen for purposes of the disclosurewhich do not constitute departures from the spirit and scope of theinvention.

What is claimed is:

1. A switch for use with two coupled units; said switch comprising:support means including a base attached to one of the coupled units andhaving an abutment surface thereon; an elongated element mounted on thebase and shiftable thereon in the direction of its longitudinal axisbetween first and second positions, the elongated element projectingbeyond the abutment surface on the base and having an abutment surfacethereon which is presented opposite the abutment sur-' face on the baseso that the distance between the abutment surfaces varies as theelongated element shifts, the abutment surfaces being spaced apart whenthe elongated element is in its second position; an electrical contactcarried by and shiftable with the elongated element; another electricalcontact mounted on the base and aligned with the contact on'theelongated element; the electrical contacts being engaged when theelongated element is in one of its positions and being spaced apart whenthe elongated element is in the other position; a spring carried by thebase for urging the elon gated element to its first position; and aspacer engageable with and positioned between the two abutment surfacesfor holding the elongated element in its second position in oppositionto the force exerted by the spring, the spacer being disengageable fromthe abutment surfaces to permit the spring to move the elongated elementto its first position, the spacer being further connected with the otherof the two coupled units so that when the units separate the spacer willdisengage the abutrnent surfaces and the spring will move the elongatedelement to its first position.

2. A switch according to claim 1 wherein the spacer is bifurcated andhas retaining arms which fit around each side of the elongated element.

3. A switch according to claim 2 wherein at least one of the arms isprovided with a notch which receives the elongated element.

4. A switch according to claim 3 wherein the notched arm has a cammingsurface leading up to the notch therein, the camming surface beingpositioned to engage the outer surface of the elongated element andconfigured to spread the arms as the arms are advanced across theopposite sides of the elongated element.

5. A switch according to claim 1 wherein the base includes a sleevethrough which the elongated element fits; and wherein the spring is acoil spring which encircles the sleeve and the elongated element.

6. A switch according to claim 5 wherein the support means includes ahousing enclosure the sleeve is fastened.

7. A switch according to claim 5 wherein the support means includes ahousing carrying a first dielectric block on which one of the electricalcontacts is mounted; and wherein the elongated element carries a seconddielectric block on which the other electrical contact is mounted; andwherein the spring at one of its ends bears against the seconddielectric block.

8. A switch according to claim 6 wherein the elongated element projectsbeyond the housing and at its outer end is enlarged, and wherein thespacer fits between the enlarged end thereof and the housing.

9. A switch according to claim 1 wherein the elongated element isenlarged at one end and the abutment surface of the elongated element ison the enlarged end.

10. A switch according to claim 9 wherein the base includes a housinwhich encloses the contacts and the elongated elemen pro ects through awall of the housing and has its enlarged end positioned externally ofthe housing, the abutmentsurface of the base being on the housing wallthrough which the elongated element projects.

11. A switch according to claim 10 wherein the spacer has spaced apartarms and an outwardly opening notch between the arms; and wherein thenotch receives the elongated element such that the arms of the spacerare between the abutment surfaces of the housing and the elongatedelement and prevent the elongated elementfrom assuming its firstposition.

Inventor) Keith G Westenhaver Signed and sealed this 15th day of May1973.-

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION T Patent'No.3,689,717 Dated September 5, 197;

' It is certified thaterror appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 6', line 8, after "enclosure" insert to which (SEAL) Attest:(EDWARD M.FLETCHER,JR-. 1 ROBERT GO'I'TSCHALK I Attesting OfficerCommissioner of Patents USCOMM-DC 6O376-P69 U. S GOVERNMENT HUNTINGOFFICE: I969 0-35-33-5 o1RM PO-1 050 (10-69) UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Da ed September 5, 1972 I Patent No. ,7l7

Inventor g I G. Westenhaver It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 6, line 8, after "enclosure" insert to which Signed and sealedthis 15th day of May 1973.

(SEAL) Attest: v v

' EDWARD M.FLETCHER JR. ROBERT GOITSCHALK Attesting Officer Commissionerof Patents USCOMM-DC 60376-P69 11 us. GOVERNMENT Pm'rmc OFFICE: 19o-aGs-au F ORM PO-1050 (10-69)

1. A switch for use with two coupled units; said switch comprising:support means including a base attached to one of the coupled units andhaving an abutment surface thereon; an elongated element mounted on thebase and shiftable thereon in the direction of its longitudinal axisbetween first and second positions, the elongated element projectingbeyond the abutment surface on the base and having an abutment surfacethereon which is presented opposite the abutment surface on the base sothat the distance between the abutment surfaces varies as the elongatedelement shifts, the abutment surfaces being spaced apart when theelongated element is in its second position; an electrical contactcarried by and shiftable with the elongated element; another electricalcontact mounted on the base and aligned with the contact on theelongated element; the electrical contacts being engaged when theelongated element is in one of its positions and being spaced apart whenthe elongated element is in the other position; a spring carried by thebase for urging the elongated element to its first position; and aspacer engageable with and positioned between the two abutment surfacesfor holding the elongated element in its second position in oppositionto the force exerted by the spring, the spacer being disengageable fromthe abutment surfaces to permit the spring to move the elongated elementto its first position, the spacer being further connected with the otherof the two coupled units so that when the units separate the spacer willdisengage the abutmEnt surfaces and the spring will move the elongatedelement to its first position.
 2. A switch according to claim 1 whereinthe spacer is bifurcated and has retaining arms which fit around eachside of the elongated element.
 3. A switch according to claim 2 whereinat least one of the arms is provided with a notch which receives theelongated element.
 4. A switch according to claim 3 wherein the notchedarm has a camming surface leading up to the notch therein, the cammingsurface being positioned to engage the outer surface of the elongatedelement and configured to spread the arms as the arms are advancedacross the opposite sides of the elongated element.
 5. A switchaccording to claim 1 wherein the base includes a sleeve through whichthe elongated element fits; and wherein the spring is a coil springwhich encircles the sleeve and the elongated element.
 6. A switchaccording to claim 5 wherein the support means includes a housingenclosure the sleeve is fastened.
 7. A switch according to claim 5wherein the support means includes a housing carrying a first dielectricblock on which one of the electrical contacts is mounted; and whereinthe elongated element carries a second dielectric block on which theother electrical contact is mounted; and wherein the spring at one ofits ends bears against the second dielectric block.
 8. A switchaccording to claim 6 wherein the elongated element projects beyond thehousing and at its outer end is enlarged, and wherein the spacer fitsbetween the enlarged end thereof and the housing.
 9. A switch accordingto claim 1 wherein the elongated element is enlarged at one end and theabutment surface of the elongated element is on the enlarged end.
 10. Aswitch according to claim 9 wherein the base includes a housing whichencloses the contacts, and the elongated element projects through a wallof the housing and has its enlarged end positioned externally of thehousing, the abutment surface of the base being on the housing wallthrough which the elongated element projects.
 11. A switch according toclaim 10 wherein the spacer has spaced apart arms and an outwardlyopening notch between the arms; and wherein the notch receives theelongated element such that the arms of the spacer are between theabutment surfaces of the housing and the elongated element and preventthe elongated element from assuming its first position.